Fibrous composition and method of producing the same



Patented Aug. 13, 1935 UNITED STATES PATENT OFFICE FIBROUS COMPOSITIONAND METHOD OF PRODUCING THE SAME British corporation No Drawing. IApplication January 11, 1934, Serial No. 706,312. In Great BritainJanuary 25, 1933 y 2 Claims. (c1. 154-2) This invention comprisesimprovements in or relating to the manufacture of compositionscontaining rubber or similar material.

The object of the invention is to produce improved materials comprisinginterlocked fibers and rubber.

Various proposals have been made for producing products comprisingfibers and rubber. Reference can be made, for instance, to a priorproposal wherein rubber cements are employed. In this earlier proposalcemented integrated fibrous sheets are produced by a method comprisingthe step of compressing an unwoven sheet of the fiber in the presence ofan excess of viscid cement, applied on one face only and advancing oneface of the sheet in respect to the other face during such compression,by a shear-like action dependent upon the presence of the viscid cement.

It is pointed out that for the fibrous body which is to be treated, aloose, flimsy web of fiber, preferably cotton, such as ordinary cardedcotton batting is employed and it is furthermore pointed out that thecarded cotton batting is usually about a quarter of an inch thick in itsuncompressed state and is formed by superposing on each other singlelaps from several carding machines to form a fleece of the desiredthickness, this fleece being either left un'sized or lightly dressed onone or both surfaces with size.

The present invention is an improvement on this particular priorproposal in that it is concerned with the use of aqueous dispersions ofrubber or the like.

Among prior rubber latex proposals we are aware, for instance, that ithas been proposed to produce cellulose caoutchouc products by bringingcellulose into the form of a loose fleece, dipping the said fleece intothe milk juice of caoutchouc hydrocarbon bearing plants, pressing offthe water, and drying the mass.

It has been suggested that products made by this process can be used asa substitute for cork, leather, linoleum, etc., as insulating materialfor electro-technical purposes.

We are also aware that it has been proposed to form compound fabricsfrom layers of fibrous material secured together by anadhesive.

It has also been disclosed to produce reinforced rubber materials usinglatex as a source of rubber by contacting with acid a jet of latexcontaining fiber or fabric, allowing thesuperflcially coated body oflatex to stand for coagulation throughout, pressing and washing thecoagulated article and drying the same.

Disadvantages are, however, -associated with all these prior rubberlatex proposals. Either, for instance, the proposed process is difficultto carry into effect or, alternatively or additionally, the productformed is not free from laminations. 5

According to the present invention the method of producing improvedmaterials comprising fibers and rubber comprises coating or treating acarded web or webs of fibers, preferably each web individually, withaqueous dispersions of the kindshereinafter specified and preferably bya spraying operation providing coagulating means for the aqueousdispersions aforesaid on the two surfaces of a, single web, if a singleweb only is employed, or on the two outermost surfaces formed by anumber of superimposed webs and consolidating the web or superposedwebs, as the case may be, by the application of pressure.

In order to prevent the materials formed showing signs of laminations,it is desirable that the aqueous dispersions aforesaid should be such asto coagulate well under the combined effect of pressure and dryingaction of the carded fibrous material.

The main difficulty to be overcome is to prevent sticking of the moistfibers of the carded web or webs to the surfaces between which thesingle web, or number of superimposed webs, is consolidated. Thisdifficulty is overcome according to the present invention, bycoagulating the layers of aqueous dispersions aforesaid on the twosurfaces of a single web, if a single web only is employed, or on thetwo outermost surfaces formed by a number of superimposed webs.Coagulation can be brought about, for instance, by .35 the use of anystronglycoagulating means, e. g., of a 5% aqueous acetic acid or 10%magnesium sulphate solution. This acid can, for example,

be wiped over any faced sheeting material between which the web or websare consolidated. This treatment ensures a thin coagulated layerat thesurface which thus leads to the production of materials of goodappearance and clean removal without sticking.

It is desirable that the aqueous dispersions be applied normally tothesurface of a web. For. example, where a web is, for instance,supported .on a drum and sprayed with the aforesaid dispersions, thisdesideratum can be obtained by directing the impinging spray along'aradius of the drum. If this precaution is not observed, the force of thespray tends to distort and spread the fibers of the web, particularly ifthe lattenis of light weight.

It has been found in certain cases desirable to employ aqueousdispersions of rubber or the like capable of yielding vulcanizedproducts of small extensibility, otherwise the final material producedis too stretchy and the two phase structure of fibers and rubber or thelike too pronounced,

t is also desirable .in working according to the present invention thatthe fibers employed should be substantially in the dry condition.

Examples of suitable fibers are those which are usually obtainable inthe carded condition, the most usual of these being cotton and wool.

The emulsions or dispersions of rubber or the like comprise thoseconsisting of rubber, guttapercha, balata or similar vegetable resinsoccurring naturally or artificially obtained. Such artificial aqueousdispersions may include those of coagulated rubber, vulcanized rubber,synthetic rubber, waste or reclaim. All of these materials, or mixturesthereof, are herein designated as rubher material. If desired, any ofthe above mentioned dispersions may be used alone or in admixture withone another.

Any of the aforesaid dispersions may contain the usual known compoundingand vulcanizing ingredients and/or may be in the first instance inconcentrated form.

Concentrates such as are obtained in Patent 1,846,164, Feb. 23, 1932, orin British Patent 219,635 to which may be added any one or more of theusual known compounding ingredients may also be employed.

The material produced according to the present invention can besubsequently given, for instance, in known manner a suede finish byspraying the material, for example, with waste wool or, may be embossedin the uncured condition in known manner.

It isalso possible to provide attractive surface markings by employing apatterned, for example, leather backing in place of smooth facedsheetmg. l

The following example illustrates how the method of the presentinvention can be effected- Example A piece of artificial leather of sixply can be made on a small scale as follows:

Faced sheeting is laid on a drum or traveling belt and wiped over with a5% acetic acid solution.

A length of carded cotton web of suitable weight e. g., 500-600 grainsper linear yard 42 inches wide is sprayed on one side with a rubberlatex mixing of 40% total solids, alkalinity 0.25:, and of the followingcomposition:

Parts by weight Rubber (in the form of latex) 100 sulphur 3 Zinc oxide 5Accelerator 0.75 Lamp black 15.0

made by adding the compounding ingredients as aqueous dispersion thereofto a rubber laweb is applied with the sprayed side downward to thetreated faced sheeting. The upper surface of this web is then sprayedwith the latex mixing. A second length or" web is laid on this sprayedsurface and the top layer of this new web is now sprayed with latexmixing. Four more cotton webs are successively superimposed and treatedin .a similar manner.

A length of faced sheeting treated with 5% acetic acid solution is thenapplied to the upper surface of the finally sprayed web layer.

The composite material is now passed once slowly between rubber rollersset for light compression. The faced sheetings are then stripped ofi andthe composite material is again passed between the rubber rollers whichare now set for high compression. The compressed material thus producedis dried and vulcanized.

What we claim is- 1. A method of producing materials comprising fibersand rubber which comprises impregnating a carded web of fibers withaqueous dispersions of rubber material without coagulating saiddispersion, superficially contacting the outer surfaces of said web witha coagulating agent to prevent said outer surfaces from sticking topress ing rolls and thereafter consolidating said webs by theapplication of pressure.

